LUA question: may I call methods from a table list?

pie

I am using TNT Particle Engine by @GregBUG, and I was wondering how I could "automate" the process of creating some particles.

I can save an array of "properties" with their respective values - like

myParticle = { [setColor] = {20,20,255}, [setSpeed] = {10,50} }   --and then call them out like this. local particle = CParticles.new(particleGFX, 0,0,0,"add") particle:setSpeed(unpack(myParticle.setSpeed)) particle:setColor(unpack(myParticle.setColor))

And this works.


May I "read" myParticle values in pairs and call the respective particle/CParticles method?

I made some tests, but the nearest I went was:

myParticle = { [setColor] = {20,20,255}, [setSpeed] = {10,50} }   local particle = CParticles.new(particleGFX, 0,0,0,"add")   local metat = getmetatable(particle) for v, func in pairs(metat) do print( v, func)   --[[ this print outputs "almost" what I think I need. I just get some methods out of all the available particle methods   setEnableAlphaMorphIn function: 0619ECCC getAlphaMorphOutEnabled function: 0619EEAC getSizeMorphOutEnabled function: 0619EE94 getColorMorphOutEnabled function: 0619EE7C setEnableColorMorph function: 0619EC24 getMaxDelay function: 0619E9B4 setMaxLife function: 0619E96C getAlphaMorphInEnabled function: 0619EE34 setSizeMorphOut function: 0619EB4C getDirectionMorphOutEnabled function: 0619EE4C setSize function: 0619EA5C __new function: 061947C4 setEnableSpeedMorph function: 0619EC0C getSizeMorphInEnabled function: 0619EE1C setLoopMode function: 0619EA44 setGravity function: 0619EA74 getSpeedMorphInEnabled function: 0619EDEC init function: 0619E920 getSizeMorphEnabled function: 0619EDA4 setSpeed function: 0619E9E4 ]]   if myParticle[v] then print_r(myParticle[v]) --this outputs exactly what I meant. particle[v](unpack(myParticle[v])) --I tought this should work end end

Here I get an error from TNT Particle Engine:
classes/tntparticlesengine.lua:1109: attempt to index local 'self' (a number value)
stack traceback:
classes/tntparticlesengine.lua:1109: in function '?'

while it was executing setSpeed (so it was "right") but line 1109 is on the wrong side of the if statement (since I provided MaxSpeed) - but This doesn't count, because I am not parsing the real "method table"/external API (how do i call it?).

I suppose I need some lua magic / guru support here: How do I get the "methods" table of a class instance?

I could follow the "bad" way of "if statements chain", but I can't believe that I can't do this with a for loop and all the wonders provided by lua

Thank you

amin13a

Hello pie.
Here it is:
particle.spec = particle["spec"]
particle:spec() = particle.spec(self)

pie

Thanks, but I think it's not exactly what I need to make this work - or I misunderstood your answer
I still can't get the "reference" to the methos of particle - and "how" do I call them?

amin13a

Hi again
The first parameter in the function particle:something() is self.
Change this line:
particle[v](unpack(myParticle[v])) --I tought this should work
To:
particle[v](self,unpack(myParticle[v])) --I tought this should work

Look at this attachment

pie

Thank you @amin13a
At least I learned something new but i still get an error

--this is the output print_r of myParticle[v]
[1] => 50
[2] => 250
--then giderosplayer FC and gives the error:
classes/tntparticlesengine.lua:1105: attempt to index local 'self' (a nil value)
stack traceback:
classes/tntparticlesengine.lua:1105: in function '?'

Which is different from previous post, this time it happens in the right side of the if statement (in setSpeed() method, so I would think that your information was right).
However it seems that this is not exactly the same thing as calling it from

particle:setSpeed(unpack(myParticle[v]))

which works seamlessly
:-?

I think I would go for the "if chain" in my project, but this info bothers me from a scientific point of view

hgy29

Hi @pie, try to use particle[v] instead of self as the first argument to your call. This should work as you expect.

pie

@hgy29

thank you for trying, but nope

classes/tntparticlesengine.lua:1105: attempt to index local 'self' (a function value)
stack traceback:
classes/tntparticlesengine.lua:1105: in function '?'

same error as before.

However, I should use a better "starting point" than particle metatable: it seems best to use my array.

let's recap, project attached if someone has a minute to share and try it out

--pairs block   myParticle = { [setColor] = {20,20,255}, [setSpeed] = {10,50} }   local particle = CParticles.new(particleGFX, 0,0,0,"add")   for property, values in pairs(myParticle) do particle[property](particle[property], unpack(values)) end

Is not the same of:

--standard block   myParticle = { [setColor] = {20,20,255}, [setSpeed] = {10,50} }   local particle = CParticles.new(particleGFX, 0,0,0,"add")   particle:setSpeed(10,50) particle:setColor(20,20,255)

How do I write the first block ("pairs block") so that it gives the same results of the second block ("standard block")?

hgy29

Sorry @pie, I meant:

particle[property](particle, unpack(values))

As @anim13a said, the first parameter to a method call is the object called itself.
particle:setSpeed(10,50) is the same as particle.setSpeed(particle,10,50).

pie

@hgy29 Thank you, it's working now.
I was sure I tried it already, but maybe I did something wrong last time..

TNT Particle editor on its way..

amin13a

Hi again.
Just copy it:
it works in my attachment.

myParticle = {
["setColor"] = {20,20,255},
["setSpeed"] = {10,50}
}

local particle = CParticles.new(particleGFX, 0,0,0,"add")

for property, values in pairs(myParticle) do
particle[property](self, unpack(values))
end

pie

thank you @amin13a

amin13a

>-

hgy29

@anim13a, beware: in your test project it works only because you don't use the self variable in your something1 or something2 functions. This is really particle that should be passed and not self, because self is not defined (i.e. is nil) at top level.

amin13a

mmm YES.
thank you hgy29.